Christmas time is coming! Pete Taylor already made super cool Christmas calendar controlled by Arduino for Concern Worldwide. Try to do your's before it's to late! Find here Pete's how-to. 

So as a spare tinkering time project I thought I would have a go at building an Arduino controlled LED advent calendar that illuminates the relevant day and counts down to the 24th.

My requirements needed it to be powered by USB, and that it’s a standalone project with it’s own date clock – as the office IT department would frown upon me installing things on my work PC to run Christmas decorations from. In order to do this I needed to read up on using a battery backed up RTC (Real Time Clock) and a way to control 24 LEDs from my arduino micro.